There are many types of rigs, vessels and structures which are required to utilize liferafts in offshore operations. The United States Coast Guard has rather severe and strict requirements for the number of rafts. These requirements relate to the number of persons onboard the offshore vessel. At present, there are many different types of techniques utilized to deploy liferafts from these rigs, vessels and/or offshore structures. Many times, the deployment of the liferafts create insurmountable and hazardous conditions under those emergency situations in which deployment is required.
Where the liferafts are required to be located at a deployment height above the water level, a liferaft davit launch system must be used. This is because it is unsafe for a "float-free" condition. The davit is utilized to pull the liferaft out of the packed container, position the liferaft for autoinflation, and hold the inflated raft in proper position for personnel to board the raft. When the davit winch brake is released, the raft is controlled-gravity lowered to the water by the davit winch box. When the raft encounters the water, the liferaft is autoreleased from the davit lowering cable.
The offshore industry has very high manpower requirements. In many types of offshore drilling rigs and construction vessels, up to seven hundred personnel are aboard. This large number of persons imposes very difficult problems as to how to furnish, store and deploy the large number of liferafts required.
At present, the United States Coast Guard has allowed and accepted liferaft davit launch systems where one launch davit is assigned to handle and launch up to four twenty-five-man liferafts from one station in a controlled sequence. The launching davits have been designed as fixed types, luffing types and slewing types.
Because of the stored liferaft packing container design and construction, the direct relation of the raft container orientation to the davit arm has been a problem of launching systems. It is often difficult to align the liferaft container with the davit arm so that the opening of the liferaft container can be accomplished.
In many offshore structures, there is a requirement that no objects protrude over the side of the vessel. As a result, it is a cumbersome and difficult task to launch the liferaft, to remove the liferaft from the liferaft container and to otherwise control the opening of the liferaft container from within the edge of the offshore structure. It is often necessary to manually move the liferaft container to the edge of the offshore structure. This can be a dangerous operation under such emergency conditions.
It is an object of the present invention to provide a liferaft launch system which presents a optimal raft container orientation.
It is another object of the present invention to provide a liferaft launching system in which, during normal operation, the liferaft containers and davit system are contained within the edge of the offshore vessel.
It is a further object of the present invention to provide a liferaft launch system which enhances the efficiency of raft deployment.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.